This work aims to develop wideband acoustic immittance (WAI) measures as a noninvasive auditory diagnostic tool, where WAI refers to the collection of measurements that include absorbance, power re?ectance, impedance, and related quantities. Potential use of these measures includes (1) detection of ?uid in newborn and young infant ears where tympanometry is less successful, (2) identi?cation of the cause of a conductive hearing loss (e.g., ?uid, disarticulated ossicle, ?xed ossicle), and (3) monitoring changes in middle-ear stiffness that result from intracranial pressure changes. The proposed work ex- tends the world's only online WAI database and corresponding website, which was developed during the ?rst cycle of this grant, from WAI measurements on normative adult ears to also include ears with speci?c pathologies and ears of babies and children. The proposed work also includes (1) laboratory- based acoustical measurements and CT ear-canal scans to understand why the two FDA-approved WAI measurement systems have systematic differences in their measurements and (2) utilizing the database to perform data analyses across studies to compare WAI measures on both normal ears and ears with speci?c pathologies in order to identify WAI features that best differentiate between normal ears and ears with speci?c pathologies. A second emphasis of the proposed work is the research-based education of undergraduate students at Smith College, an all-women's liberal arts college. Undergraduate engi- neering students will be actively involved in all areas of the proposed work, with the goal of encouraging them to continuing their education at the graduate level.